Galvanometer



Dec. 26, 1950 C. A. HEILAND GALVANOMETER Filed Aug. 11, 1944 5 Sheets-Sheet 1 fn'venior Car l Jieiland flz orizgs.

Dec. 26, 1950 c. A. HElLAND 2,535,065

GALVANOMETER I Filed Aug. 11, 1944 1 5 Sheets-Sheet 4 Patented Dec. 26, 1950 GALVANOMETER.

Carl A. Heil'and, Denver, 0010., assignorto Heiland Research Corporation, Denver, Colo., a corpo ration oi Golorado Application Augustll, 1944 SerialNO. 549,105

MsGlaims. I

This invention relates to a recording, and indicating galvanometer capable of a wide variety of uses and particularly adapted for use in a,re cording system wherein an immediately visible and permanent record is. made of electrical or other phenomena of an oscillatory or varying character through the use of essentially invisible radiations, which system is. described and claimed. in a copending application, Serial No. 549,104,. filed August 11, 1944.

A galvanometer ordinarily comprises a magnet terminating in pole pieces between whichthere is mounted for oscillatory movementa suspended coil arranged for connection in an elec-.. tric circuit in which the phenomena to, be studied are present and a mirror or pointer attached to or movable with the coil gives an indication of the nature of the oscillations which: are firesent in the circuit. One object of the present inven; tion is to provide an improved galvanometer comprising the fundamental parts. referred to, in which a compact and highly sensitive, arrangement is provided by locating all of the principal parts except the mirror in the plane of incidence, that is, the plane in which light rays or other rays pass to and are reflected from the galvae nometer during its operation. To attain this ob jective, the dimensions of the magnet and pole pieces at right angles to the plane of incidence are as small as possible, thus: facilitating the con-r struction of a multiple galvanometer comprising;

magnetic fields which are parallel. to each other and which lie in the planes of incidence of theirrespective mirrors, while the planes of the coils are also in the planes of incidence and at right.

angles to the planes or axes of the mirrors, A

further object of the invention is to provide angaps in which are located the opposite parallel 5 arms of the coil or winding which is supported entirely b means located outside of said air" gaps. A further object of the invention is to provide a galvanometercomprising pole. races and an intervening field piece in combination with an improved suspension of the vibratory coil which is so mounted that it may be adjusted laterallyof' the axis of oscillation to position the coil prop erly' in the air gaps, While also permitting ad'- jiistment of" the tension of; the suspension ribbon in order to regulate the sensitivity of the device. Ifhe invention also comprises means for regulating the admission to the galvanometer mirror of the rays which are reflected therefrom durin its use for indicating or recording purposes. Other Qbjects relate to various features. of construction and arran ement which wil appear m e. l y hereinaf en The. a r of the inv n i n. wi l be under d. from the followin specificati n a niwith the ac mpanying. drawing in which ne mbodiment is illustrated in. association w th n m. of recordin ppara u In. the draw n s.

Fi r 1, shows. a vertical. section ro h one form of re ordin pparatus which, in lu s he ealvanometer f'the, present invention, the a lr nometer o prisin a plur lity of. sep r te nit which a e llus rated inv nd elevation;

Fig. 2 is a,v perspective view of the lower part. offthe galvanometer and associated. parts,v illustrating the, means [or controlling the radiation admitted tothe galvanometer mirrors and. the. means. for periodically reflecting beams. oi invisible radiations which are adapted to 150.131).v spaced timelines ona sensitizedfilm which. sv employed in the recording apparatus;

Fig 3, shows a vertical s c ion through one f the ealvanometers em odied in. the. apparatus i1.- lu tr -ted in Fisl and hr h: cert i part of th recordin pparatus which are as ociated therewith;

Fig. 4 shows a sectional view taken on the line 4,4 of Fig. 3;

5. shows. a. vertical section taken thr u h. thecasing of, the recordin a paratus and illustrat s front elevation. t e. salvano eter o .hopresent. inventi n som of the parts b n br n aw and ome or aalvenometers b ng; shown in front elevation w ile. oth rs are. shown partially in'vertical section;

Fig. 6 shows a top plan view of the galvanometer illustrated in Fig.

Fig. 7 shows an enlarged vertical section through one end portion of the receiving mirror assembly which is illustrated in the left-hand part of Fig. 3, showing the means for effecting the vertical and angular adjustments thereof;

Fig. 8 shows a vertical section through one end portion of the projection mirror illustrated in the left-hand portion of Fig. 3 with associated parts of the apparatus, illustrating the means for adjusting the normal angular position of this mirror;

Fig. 9 shows a horizontal section taken on the line 9-9 of Fig. 3 through one of the individual galvanometers, illustrating the structure of the field and armature cores;

Fig. 10 is a perspective view of the side plates which form the housing of each galvanometer;

Fig. 11 is a partial enlarged vertical section through one of the galvanometers, similar to the section illustrated in Fig. 3, showing in greater detail the structure of the individual parts; and

Fig. 12 is a partial vertical section taken on the line l2l2 of Fig. 11.

In the accompanying drawings, the present invention is illustrated as being embodied in a multigalvanometer employing a plurality of separate units which are arranged Side by side and which may be employed in the simultaneous study and recording of several different electrical phenomena which are represented by oscillations in separate electrical circuits. This galvanometer is illustrated in connection with the recording apparatus which is described and claimed in the above-mentioned copending application in the use of which invisible radiations such as ultraviolet rays or infra-red rays are caused to be reflected by cylindrical mirrors to the mirrors of the individual galvanometers which are also preferably cylindrical in form, and these galvanometer mirrors, which are caused to oscillate in response to the oscillations present in the electric circuits under investigation, reflect their beams to a receiving mirror, also preferably of cylindrical form, which directs the beams 'of the several galvanometers to the surface of the moving film which is so sensitized that it is responsive only to the invisible radiations being employed. This film reacts immediately to produce a permanent record of the oscillations, which record may be viewed through a filter forming a portion of the Wall of the housing in which the apparatus is contained, this filter being of such a nature that it screens out the invisible radiations which are employed in making the record While permitting the record on the moving sheet to be viewed in daylight. With this preliminary explanation, the more general features of the recording system will be described preliminary to setting forth the details of the improved galvanometer which is embodied in this system.

As illustrated particularly in Figs. 1, 3 and 4, the recording apparatus comprises a portable housing having mounted in the upper part thereof an auxiliary casing 26 containing the source of invisible radiations which, in this instance, are illustrated as a bulb 2? adapted to be connected in an electric circuit and embodying a tube 28 adapted to emit the invisible radiations which may be ultra-violet rays or infra-red rays, or combinations of these rays, depending upon the character of the bulb which is used. These rays pass downwardly through a slot 26 in the bottom of the auxiliary casing 26 along a line 29 and impinge upon the concave surface of a cylindrical projection mirror 30 which is so designated because it is constructed as an arcuate segment of a complete cylinder with its axis extending horizontally. This mirror is adjustable angularly and the invisible rays pass from its surface along a line 3| to the concave surfaces of a plurality of cylindrical galvanometer mirrors 32 which are mounted to oscilate with the movable elements of a plurality of closely arranged galvanometers 33 constructed according to the principles of the present invention. These galvanometers are arranged side by side and each one is connected by a cable 35 with a source of electrical oscillations to be studied with the use of the recording apparatus. The mirrors of these galvanometers oscillate about vertical axes in response to the oscillations in the respective circuits to which they are connected and the beam of invisible radiations 36 which is reflected from each galvanometer mirror 32 is thus caused to oscillate as it passes to a receiving mirror 3'! which is constructed as a segment of a cylinder and which is common to all of the galvanometers so that the inivisible beams 36 received from the galvanometer mirrors are reflected downwardly along the lines 38 through an opening 39 in a shield or apron 39, to the sensitized film or paper 45 upon which the permanent record is made, this sheet being sensitized so that it is responsive only to the kind of invisible radiations which are being produced by the tube 28. A part of the invisible rays reflected from the galvanometer mirrors 32 passes between the mirrors 30 and 37, along the line 4!, and these rays impinge upon the surface of a fluorescent coated screen 34, resulting in a bright line on that screen which indicates the fluctuations of the galvanometer mirrors to the observer through a slot 39 which is formed in the apron 39 and positioned opposite the filter screen 42 forming a substantial part of the front wall of the case or housing 25 and formed to screen out from the outside light the invisible radiatibns which are employed in producing the record on the sensitized film.

The filter 42, which thus excludes the invisible radiations passing from the bulb 21, serves to permit the operator to View the permanent record which is formed on the film or paper 48 by the oscillating beams 38 directed thereto from the receiving mirror 31. The sensitization of the film being such that a permanent record is immediately made, this record may be viewed as the film passes downwardly in the direction of the arrow 43 in front of a guiding plate 44. The film is continuously supplied from a magazine 45 containing a drum or reel upon which the sensitized paper is wound and, after passing over the guide plate 44, the exposed portion of the film is wound up on another reel or drum, not illustrated, so that the film is continuously withdrawn from one magazine and continuously wound up on a drum in. another magazine during the operation of the apparatus.

As illustrated in the drawings, the case or housing 25, in which the recording apparatus is mounted, comprises a back wall 53 having hinged thereon at 8G a top wall or cover "it? which is adapted also to serve as a closure for the auxiliary casing 26 when it i in closed position. At the front of the housing, the apparatus is enclosed by a door in which the filter s2 is mounted, and the upper edge of this door overlaps a transverse frame member ll having attached thereto a hinge 18 about which the auxiliary casing 26 and assesses its contents maybe swung forwardly out of the. housing .25 when the cover H! has been elevated. The casing. 26 has side walls 86, a back wall 8'? anda front wall 88, all of which are attached to a bottom. wall. 85, thus forming an enclosure. of rectangular cross section to receive the bulb 21 which projects through an aperture 88 in the forwardwall of the casing. 'Ihebulb is enclosed by a metal tube 88 which. is closed at. its forward end and. which projects through an aperture in the rear wall. 81., terminating in the screw threaded stem portion which engages a socket 94. This socket is located in a sleeve 92 which is securedto a ring at attached to the rear end of the casingifi and the rear end of the sleeve is closed by a disk 93 having an aperture therein through which extends a cable 98 containing the conductors which lead from a source of electrical energy to the socket at, so that the tube 28 isthereby energized to produce the invisible radiations. A conduit 88 is adapted to convey air under pressure to the casing 26 for the purpose of cooling the bulb during its operation. The shell 90 which encloses the bulb 21 is provided on its under side with a slot 96 registering with the slot 26 previously referred to so that the in isible radiations proceeding from the tube pass downwardly along the line 29 to the projection mirror 30 comprising a mirror proper which is mounted upon a backing plate and provided at its ends with relatively fixed trunnions H39, shown in Fig. 8, which are journaled in bearings formed in bearing plates llll attached to the under side of the bottom wall of the casing 25. One of the trunnions has adjustably mounted thereon by means of a set screw sea a laterally projecting arm H13 which extends between two lugs HJI and lfll formed on the adjacent bearing plate It. The lug Hill is socketed to receive a coil spring I04 which engages the under side of the arm [03, and the upper side of this arm is engaged. by an adjusting screw I05 having a threaded engagement with the lug IQ I and with the. bottom wall 85 of the auxiliary casing. When the top cover 79 of the housing has been elevated, the screw [55 is accessible for the purposeof adjusting the angular position of the arm [03 and the corresponding angular position of the mirror 39, which adjustment may be required in order to cause thebeam 3| of invisible radiat ons normal position of the arm ass on its trunnion Hill, a wide range of adjustability may thus be obtained.

The receiving mirror 31 is also adjustably mounted, as shown particularly in Figs. 3, 4 and 7, and it is also capable of adjustment vertically in. order to. vary its spaced relation to the fi m or paper 4.0.. its backing plate are provided with longitudinally extending trunnions I95 which are journaled in bearing. plates to! and which slidably engage elongated slots, was formed in supporting plates I138 mounted on. the bottom wall 85 of the auxiliary casing and constituting the end wals of the apron or shield 39-, previously referred to, which encloses. the mirrors 3?! and 31 except on the inner sides thereof which are directed toward the galvanometer mirrors 32. These end plates I08- are. shaped to coniorm to the configuration of the apron 3.9 and the bottom wall 39 of the apron, which hasv the slot, 3.9a formed therein, is extended rear-wardly beyond the end plates I08, as

For this purpose, the mirror 3'? and shown in Eigs. 1 and 3, in order to protect the sensitized film or paper 40 from all light rays or other rays except the invisible radiations. which pass thereto through the slotv 39?. The end plates. Hi8 are also provided with elongated slots H18 9, located in vertical alignment with the slots teas and arranged to. be engaged by pins H0 which extend from. the upper portions of the plates I91. Theupper parts of the plates It! are provided with lugs m which are threadedly en:- gaged by adjusting screws Ill which extend upe wardly through the bottom plate of. the auxile iary casing, being provided above this wall with heads Ill adapted to be engaged by a screw driver for regulating the elevation of the plates H11 with respect to the supporting plates I08, thereby varying the spaced relation of the mirror 31 and the portion of the film iil which is located beneath the slot 39 One end of the mirror 3! is provided with a rearwardly extending arm 9 i2 which is provided with an aperture loosely engaged by the lowerunthreaded portion of an adjusting screw H3- which extends upwardly and threadedly engages an aperture in a lug Hil carried by the adjacent plate Hill. The upper threaded end of this adjusting screw extends through an aperture 85 in the bottom wall 85 of the auxiliary casing and the notched end of this screw may be engaged by a screw driver for regulating its position in the lug Hil A coil spring H4 is mounted around the lower end of the adjusting screw between the lug Hll and the end of the arm 2 and normally serves to maintain the arm i l2 against the head 3 of the screw so that, when the screw is adjusted in the lug lil'l the angular position ofthe mirror 31 is varied in order to cause the beam 33 of invisible radiations to pass properly through the aperture 39 in the shield 39.

The galvanometers 33 which include the recordin mirrors 32 are arranged in a group in parallel relationship at the rear of the cabinet 25 where they are supported by a pair of par allel brackets H5 secured to the back plate 63- and extending horizontally therefrom. In the embodiment illustrated, there are six identical galvanometers supported by and between these brackets, this being a convenient number for the simultaneous study and recording of a number of electrical phenomena. The galvanometers are so constructed that their dimensions are comparatively small measured transversely to the plane of incidence of the invisible rays, that is, the plane determined by the lines 3| and 36 for each galvanometer. The magnetic fields of adjacent galvanometers are parallel to each other and parallel to or coincident with the planes of incidence and the coils of the movable elements of the galvanometers also occupy these planes of incidence with the mirrors 32 mounted at right angles to those planes. To accomplish this arrangement, each galvanometer 33 includes a. permanent magnet H6 having attached to its opposite arms two pole pieces II? which, in effect, form continuations thereof. These pole pieces are provided with opposite pole faces l the dimensions of which are very limited, measured transversely to the plane of incidence, as shown in Fig. 9, this result being accomplished by tapering the magnetizable material of these pole pieces onopposite sidesof each pole face, as indicated at I I, the two surfaces l-ll of each pole piece making an angle of about 60 degrees with each other. The magnet H6 and the pole pieces H1 or each galvanometerare mounted between a pair of non-magnetic side plates II8 and H9 which have the form shown particularly in Fig. 10, and a stationary field piece or armature core I20 is mounted between the pole faces Ill The method of assembly of these parts is shown particularly in Figs. 1, 5, 6, 9, 11 and 12. The pole pieces II! are first placed against the lower part N8 of the plate II8 which is shaped to conform to the contour of these members and are secured thereto by screws IZI. The stationary field piece or armature core I25 is attached to the side plate Iii? by means of a non-magnetic spacing block I22 which is attached to the plate H8 and engaged by screws I23 which pass through the identical complementary parts I25 of the field member I20. The complementary members lit are provided with vertically extendin recesses which form a vertical channel I25] of rectangular cross section which is adapted to receive a tubular member I24, formed of aluminum or the like and mounted upon the suspended shaft or ribbon I 25 formed of gold alloy or the like which carries the movable coil I21 of the armature. The parts I23 of the field piece I25 are tapered along their vertical edges 825 so that their vertical faces are of the same width as the pole faces II'I from which they are spaced by air gaps I28. After the field piece 25 has been mounted on the block I22 to form the air ga s I28 of equal dimensions, and after the coil I27 has been assembled and placed in its proper position, as hereinafter described, the magnet H3 is put in place against the bottom faces of the pole pieces Hi and the side plate H9 of the galvanometer is attached by screws 52%; or the like to the field pieces ill, with the flange H of this plate extending below and supporting the magnet, thus forming a unitary structure.

In the assembly and mounting of the arma ture, cross bars me are secured to the upper and lower portions of the tube I24 to extend parallel to each other and form a frame for the armaturo coil I2! which is formed by winding relatively small insulated copper wire 835, such as gauge 46 cop-per wire insulated with Bakelite enamel, about the cross bars. After mounting the mirror 32 on the upper nd of the tube $24, the ribbon I25 is threaded through the tube and the coil is placed over the back member H25 of the field piece with the tube i245 engaging the rear recess I25 the member lfifi being then held by pins on the block I22 which is brazed or otherwise secured to the side plate i it. Thereupon, the upper and lower ends of the rib hon are secured by their clamping devices, hereinafter described, and. the tube H24 is adjusted verticall to the proper position on the ribbon and then secured to the ribbon. After adjusting the ribbon laterally, as hereinafter described, to position the coil properly in the air gaps and to position the tube in the recess 52% the front member is put in place and the screws 523 inserted to hold the field piece in position. This method of construction locates the supports for the coil entirely outside of the air gaps I28 so that a maximum of space is allowed for the portions of the windings which extend through the gaps. The vertical stretches of the coil occupy positions midway of the gapsi28 and the coil 52'; is thus free to oscillate about the axis of the ribbon I25, being influenced by the current, the torsion of the ribbon and the action of the magnetic field,

The side plate IIB has an upwardly extending part of rectangular outline which is provided along its front edge with a transversely extending flange HI? and along its rear edge with a transversely extending flange H8, which flanges terminate at their upper ends in inturned lips II8 having their outer surfaces lying flush with the upper end of the body of the plate, thus forming an enclosure for the ribbon I25 and its upper mounting as well as for the mirror 32 which is mounted on the upper end of the tube I24. The forward flange II8 of the plate H8 is provided with a square opening I I8 which provides a passage for the beam 3I passing to the mirror 32 and for the reflected beam 36 passing therefrom, as shown in Fig. 3. The lower part IIl-I of the side plate H9 is shaped to conform to the outline of the magnet H6 and the pole pieces Ill and its upper rectangular extension IISJ of the other side plate is adapted to fit against the outer margins of the flanges II8 and II8, thus completing the enclosure or housing in which the upper part of the ribbon I25 and the mirror 32 are mounted. The plate H9 is provided at its bottom with a transverse flange H9 which underlies and supports the magnet I I6.

The mounting of the ribbon I25 is illustrated particularly in Figs. 5, 6, 11 and 12, where the upper end of the ribbon is illustrated as being secured in a clamp I3I mounted on the lower end of a shank I32 which is keyed within a tubular metal torsion head I33. An insulating connector block I35 is seated upon an insulating plate I35, formed of Bakelite or the like, and this block I35 has a vertical aperture in which there is secured a metallic bushing I31 arranged to fit over the torsion head I33. The plate I35, to which the torsion head I33 is secured, is provided with elongated slots engaged by screws I36 which enter threaded holes in the lips I I8 formed on the upper end of the side plate H8 so that, by loosening the screws, the plate I 35 and the parts mounted thereon may be shifted with respect to the plates H8 and H9. The lower part of the torsion head I33 is threaded to pass; through an aperture in the plate I35 and the lower end thereof is engaged by a nut I38, thus clamping the torsion head frictionally in position. The upper end of the shank I32 is threaded for engagement by an elongated nut I39 which is notched at its upper end for engagement by a screw driver or the like and which has an annular undercut flange I39 rotatably engaging an annular groove I33 in the torsion head so that upon rotation of the nut I39 there is eifected an endwise movement of the shank I32 which is splined to the torsion head I33 by a pin or screw I32 thereby regulating the tension of the ribbon I25. The notches I33 in the upper end of the torsion head I33 may be engaged by a spanner wrench or the like and the entire torsion head may be thus rotated, against the frictional resistance exerted by the clamping nut I38, to carry with it the ribbon I25 and thereby adjust the position of the mirror 32 so that the beam 3| received thereby will be properly directed along the line 35 to the mirror 31.

At its bottom end, the ribbon I25 is secured in a clamp I42 fixed on an insulating plate I43 which is provided with elongated slots engaged by screws I44 by which the plate is clamped to the side plate IIB of the galvanometer at a point slightly above the lower part of the magnet IIG. By loosening the screws I36 and the screws I44, both of the insulating plates I35 and I43 may be adjusted simultaneously on their supports to cause the vertical portions of the coil I21 to occupy the proper positions within the air gaps I28.

One end portion of the wire I36 which forms the winding of each galvanometer coil is extended loosely to an insulated terminal post Hi mounted on the flange IIii of the side plate M8, as shown in Fig. 11. The outer part of this terminal member is slotted for engagement by the bifurcated lower end of a metal clip I45 which extends upwardly and is secured by a terminal screw I41 to one end'of the Connector block I3 where it is attached to one wire 35 of the supply cable 35 through which electrical oscillations to be studied and recorded are received. The other wire 35 of this electrical connection is soldered to a flange formed on the upper end of the metallic bushing I31, thus forming an electrical connection through the torsion head I33 and the shank I32 with the ribbon 525 to which the other end of the wire I is soldered or otherwise secured in the region of the coil I21. The metal bushing I31 fixed in the connector block I34 fits over the torsion head I33 and the entire block I34 and the parts carried thereby may be lifted out of engagement with the tor- Sion head and the terminal post I45 to disconnect the supply conductors from the galvanometer.

The ribbon I25 is constructed as a comparative'ly narrow flat member occupying a plane which is parallel to or coincident with the plane of incidence of the beam coming to the mirror 32 so that the oscillation of the coil 'I2I sets up a torsional strain in the ribbon which tends to return it and the mirrorto their normal positions. This arrangement of the fiat ribbon I25 with respect to the plane of incidence of the beam also has the advantage that it keeps the optical dimensions constant, since the coil will not vibrate toward and from the source of radiations under the influence of the vibrations of adjacent machines or the like. Thus, incidental vibrations are less likely to effect the optical reproduction. By adjusting the nuts I39 at the upper ends of the shanks I32, the tensions of the ribbons I25 of the various galvanometers may be regulated in order to adjust the sensitivity of the galvanometers to the os-i lations in the e ectric current traveling through the coils I21. By adjusting the torsion head I33 of each galvano'met'er angularly on its supporting plate I35, the con nested mirror 32 may be regulated in its position so that the beam 36 reflected therefrom will impinge upon the mirror 31 and be directed to the proper position on the film or paper.

In addition to the adjustments just mentioned, provision is made for adjusting the ga'lvanometers bodily on their supporting brackets I i5 about the longitudinal center lines of the reflecting surfaces of their respective mirrors 32, thus causing a vertical adjustment of the positions of th b am so that it will be reflected properly to the mirror 31. The means for effecting this angular adjustment of the galvanometers are shown particularly in Figs. 1, 3, 5 and 6. Mounted on the supporting brackets H5 at the front and rear sides of the galvanometers are a pair of supporting bars too which are secured to the brackets with rubber blocks I5-I interposed between the brackets and their under sides to provide a somewhat resilient mounting for the gal-vanometers so that they will be less subject to vibrat ons of other objects. These sup orting bars I50 are provided with nowardly extending arcuate bearing surfaces IBM which are concentric with the center of the cylindrical ffiilfol's 32 0f the galvanomete'r's. as illustrated particularly in Fig. 3. The side plates I18 and IIS of each galvanometer are provided on their front and rear edges with projections B and I I9 respectively, which have lower bearing surfaces concentric with the surfaces I5Il so that these projections may rest edgewise on the bars I51! and permit angular adjustment of the field structure of the galvanometer and all other parts thereof about the longitudinal center line of the reflecting surface of the associated mirror 32. At each side of each galvanorneter, an angle bracket I52 is secured to the pole piece I H by a screw l53, the vertical flange of each bracket lies between two of the projections II8 and I I9 and the to flange thereof lies flush with the upper surfaces of these projections. The top flange or each bracket is provided with an elongated slot I52 engaged by a threaded stud I54 secured in the underlying bar 150. The upper ends of these studs are engaged by clamping nuts I55 which are slotted for engagement by a wrench or screw driver so that they may be adjusted to clamp the galvanometer in position or release it so that it may be angularly adjusted in the manner de scribed. In this way, the several g'alvanometers '33 may be independently adjusted on the supporting bars I59 in order to cause the beams 36 reflected therefrom to strike the mirror 31 in the proper locations.

In the recording system herein described, means are preferably employed for changing the speed of movement of the film or paper all, as set forth in sa d copending application, and, in order that proper results may be obtained when operating at different speeds, apparatus has been provided in association with the galvanometers for cutting down the radiations admitted to the mirrors 32 when operating at low speeds and, in addition, means have been provided for automatically marking the sensitized film or sheet with equally spaced time lines appropriate for the speed at which the film is moving. The means for reducing the amount of light admitted to and reflected from the galvanorne'ter mirrors 32 when operating at a low "speed includes a shutter I60 which normally occupies a horizontal position, as shown in Fig. 3, and which is adapted to be swung upwardly to the position shown by dotted lines in Fig. 2. This shutteris -in the form of a thin flat plate having a plurality of square apertures 55!! formed therein which are located so that, when the shutter is in its upright position, each of the apertures Iii!) will be located opposite one of the square apertures us in the galvanometer casing.

The'apertures Nit are substantially smaller than the apertures I 98 so that, when the shutter is in its upright position, the invisible radiations pass-- ing to and reflected from each galvanomete'r mirror 32 are substantially reduced, which is desirable in order to prevent overexposure of the film w en moving at low speeds. The shutter I60 is mounted on a small shaft I6! which has one end secured to a piston I62 mounted to travel in a cylinder I63 in which there is a coil spring I64 tending normally to move the shaft and its shutter toward the right, as viewed in Figs. 2, 5 and 6. The other end of the shaft ISI is secured to a plunger I55 which is slidably mounted in a sleeve I66 at the right end of the apparatus, as viewed in Figs. 2, 5 and 6. The sleeve I66 is rovided with a helical slot Nit engaged by a pin I which is fixed on the plunger I55. The cylinder I63 and the sleeve I 65 are secured in aper.-.- tures in two supporting plates I68 which have their lower ends pivotally mounted on screws I69 engaging the threaded apertures in the brackets II by which the galvanometers are supported.

The plates I68 normally occupy the elevated positions shown in Figs. 1, 2 and 5, in which positions the rearward swinging of these members is lirn ited by pins I fixed in the brackets H5. The

'members I68 are normally held in their upright positions by leaf springs I1I which are secured to the under sides of the brackets H5 with their free ends pressing against the flat surfaces I68 which are formed on the lower ends of the members I68. When it is necessary to have access to the galvanometers from the front, the supporting plates I68 and the parts carried thereby may be swung downwardly and forwardly to permit removal of the galvanom ter. With this mounting of the shutter I60, it will be apparent that, upon pressing inwardly toward the left on the plunger I65, the inclined slot I655, coacting with the pin I61, will rotate the shaft IGI and thus elevate the shutter to its upright position. This movement is brought about automatically at the time of changing the speed of operation of the camera, by a shaft I12 which extends vertically at one side of the group of galvanometers and which has mounted thereon a rearwardly extending arm I'-'3 positioned opposite the end of t e pl nger I65, as shown particularly in Fig. 2. This shaft I12 is provided near its low r end with a rearward y projecting arm I14 which is pivotal y connected to a shift rod I15. throu h the op rat on of whi h the change from a minutel rate of r cording, for example, to an hourly rate, is effected. as hereinafter set forth. When the shi t rod I15 is actuated to chan e to the slower rate of op ration. t e a m I13 o t e sh ft I12 is at the same time moved toward the left. as viewed in t e dra in s, to move the shutt r IN! to its upper position and thereby restrict the galvanometer openings.

The lat s H 8, wh ch are nivotal'y mount d on the brackets H5. a o erve to support a concave c lindrical mi ror I 1 whi h is fixed on a sha t I18 .iournaled in th forward o tions of the plates I68 in s ch positions that the mirror I11 occupies a posit on just b lo t o er margins of the aivanom ter o n ngs IHi and in front of the sh tter I80 hen the h tt r is n it o mal hori'zontal o ition. as shown in Fi s. 2 and 3. The shaft I"! is p ov ded at he en a jament the shaft I 2 with a crank arm P9 hich is engaged by a leaf sp ing I "I! attached to the adiacent su zmo tina plate I38 and ada ted to turn the mirror I11 to a posit on where it will direct a part of the rays received from the m rror to the mirror 31. The crank am I19 has a projecting part I19 which lies in the path of movement of the end portion IRI of a t ip le er I8I of bell crank form which is p ot d by a in I82 on a lower part of the shaft I 2 so t at the lever turns with the shaft. Th s trip lever has a horizontal arm I8I terminating in a down ardly extending finger I8I which is adapted to be actuated at the end of each minute when the apparatus is operating at a minutely rate and at the end of the hour when the apparatus is operating on an hourly rate. With each downward movement of the arm I8I the crank arm I19 is released by the extremity I8I of the lever which passes loosely through an aperture in the upper part of the shaft I12 and the crank arm I19 is thereby rotated by the spring I80 to cause the mirror I11 to reflect a part of the rays passing from the mirror 30 directly to the mirror 31,

12 independently of the galvanometer mirrors, so that an invisible radiation is thereby directed momentarily onto the surface of the film to form a horizontal time line.

It will be observed that in each galvanometer of the galvanorneter system described above, the use of a cylindrical mirror 30 provides a line source of invisible radiations, as distinguished from a point source. These radiations are reflected to the cylindrical mirror 32, having its axis parallel to the axis of rotation of the galvanometer, and this mirror reflects the rays of the concentrating cylindrical mirror 31 by which they are directed to the paper. This is a very eiiicient system from the optical viewpoint, since the mirror 31 causes the image of the line source to be concentrated onto a spot with such increased intensity as to obtain an immediately visible image.

Although one form of the invention has been shown and described by way of illustration, it will be understood that it may be constructed in various other embodiments without departing from the scope of the appended claims. The term oscillatory as used in the claims to refer to phenomena which may be studied with the use of the galvanometer of the present invention is to be construed broadly to include any phenomena which vary with time and is not limited to fluctuations which are continuous or regular in their manifestations.

I claim:

1. An electrical galvanometer comprising, a pair of metal side plates formed of non-magnetic material, a magnet and pole pieces mounted between and contacting on their sides with said side plates. a ribbon carried by said side plates and extending between said pole pieces, a coil carried by said ribbon between said pole pieces, said ribbon having its plane extending in the direction in which flux passe between said pole pieces and extending through and in opposite directions from said coil, and a mirror mounted on said ribbon.

2. An electrical galvanometer comprising, a pair of metal side plates formed of non-magnetic material, a magnet and pole pieces mounted between and contacting on their sides with said side plates, a field member secured to one of said side plates between said 'pole pieces and spaced from said pole pieces, a ribbon fixed in supports by said side plates, and a coil carried by said ribbon and having parts movable in said air gaps, said ribbon having its plane extending in the direction in which flux passes between said pole pieces and extending through and in opposite directions from said coil.

3. An electrical galvanometer comprising, a pair of sheet metal side plates formed of nonmagnetic material, a magnet and spaced pole pieces mounted between and secured to said side plates, said side plates having parts extending above said pole pieces and provided with transverse flanges to form a housing, a ribbon having its upper end adjustably mounted on certain of said flanges and suspended between saidpole faces, a coil mounted on said ribbon, and means for mountingthe lower end of said ribbon for lateral and endwise adjustment on one of said side plates.

4. An electrical galvanometer comprising, a pair of sheet metal side plates formed of nonmagnetic material, a' magnet and spaced pole pieces mounted between and secured to said side P1 2 1 5, said side plates having parts extending 13 above said pole pieces, a field member secured to oneof said side plates and positioned between said pole pieces to form air gaps, said field member having a vertical aperture therethrough, a ribbon freely passing through said aperture, a coil mounted on said ribbon and having parts extending through said air gaps, and means for adjustably securing the ends of said ribbon to one of said side plates to permit lateral adjustment of said ribbon to position said coil in said air gaps.

5. An electrical galvanometer comprising, a pair of sheet metal side plates formed of nonmagnetic material, a magnet and spaced pole pieces mounted between and secured to said side plates, said side plates having parts extending above said pole pieces, a field member secured to one of said side plates and positioned between said pole pieces to form air gaps, said field member having a vertical aperture therethrough, a ribbon extending through said aperture, a coil mounted on said ribbon and having parts extending through said air gaps, means for adjustably securing the ends of said ribbon with respect to said side plates to permit lateral adjustment of said ribbon to position said coil in said air gaps, and means for adjusting the longitudinal tension in said ribbon.

6. An electrical galvanometer comprising, a magnet having spaced pole pieces, a fieid member mounted between said pole pieces and. spaced therefrom to provide air gaps, a coil extending around said field member and through said air gaps, a vertical ribbon carrying said coil, means for holding said ribbon below said field member, an insulating plate mounted above said field member, a torsion head mounted on said plate, means for securing the upper part of said ribbon to said torsion head, and means for adjusting said insulating plate bodily transversely of said ribbon.

7. An electrical galvanometer comprising, a magnet having spaced pole pieces, a field member mounted between said pole pieces and spaced therefrom to provide air gaps, a coil extending around said field member and through said air gaps, a vertical ribbon carrying said coil, means for holding said ribbon below said field member, an insulating plate mounted above said field member, a torsion head mounted on said plate, means for securing the upper part of said ribbon to said torsion head, means for adjusting said insulating plate bodily transversely of said ribbon, a mirror carried by said ribbon, and means for adjusting said torsion head angularly on said plate.

8. An electrical galvanometer compr sing, a magnet having spaced pole pieces, a field mem ber mounted between said pole pieces and spaced therefrom to provide air gaps, a coil extending around said field member and through said air gaps, a vertical ribbon carrying said coil, means for holding said ribbon below said field member, an insulating plate mounted above said field member, a torsion head mounted on said plate, means for securing the upper part of said ribbon to said torsion head, means for adjusting said insulating plate bodily transversely of said ribbon, a mirror carried by said ribbon, means for adjusting said torsion head angularly on said plate, and means for adjusting said ribbon end- Wise with respect to said torsion head.

9. An electrical galvanometer comprising, a magnet having spaced pole pieces, a field member mounted between said pole pieces and spaced therefrom to provide air gaps, a coil extending around said field member and through said air gaps, a vertical ribbon carrying said coil, means for holding said ribbon below said field member, an insulating plate mounted above said field member, a torsion head mounted on said plate, a shank splined in said torsion head, and a nut threadediy engaging said shank and contacting said torsion head for adjusting the tension of said ribbon.

10. An electrical galvanometer comprising, a magnet having spaced pole pieces, a field member mounted between said pole pieces and spaced therefrom to provideair gaps, a coil extending around said member and through said air gaps, a vertical ribbon carrying said coil, means for holding said ribbon below said field member, an insulating plate mounted above said field member, a torsion head mounted on said plate, a shank splined in said torsion head, a nut threadedly engaging said shank and contacting said torsion head for adjusting the tension of said ribbon, and means carried by said insulating plate for forming electrical connections with the terminals of said coil.

11. An electrical galvanometer comprising, a field structure having pole pieces and a source of magnetic lines of force, a ribbon fixed at its ends with respect to said field structure, a coil mounted on said ribbon for oscillatory movement between said pole pieces, a concave cylindrical mirror mounted with its axis extending vertically and parallel to the axis of said ribbon for movement with said coil, and means for ad- ,iusting said galvanometer bodily about the center of said mirror.

1 A galvanometer comprising, a field structure including spaced opposed magnetic poles and a source of magnetic lines of force, a coil mounted for rotation on an axis between the opposed poles, a mirror associated with the coil so that it moves with the coil about an axis parallel with the coil axis, a source of radiation adapted to be directed to the mirror and refiected therefrom to be recorded, and means for ad usting the field structure and its poles together with the coil and the mirror so they will move as a unit about a center coinciding with the pont of reflection of the mirror and in a plane eXtEnding in a direction parallel to the magnetic field passing between the poles.

13. A galvanometer comprising,.a field structure including spaced opposed magnetic poles and a source of magnetic lines of force, a coil mounted for rotation on an axis between the opposed poles, a mirror associated with the coil so that it moves with the coil about an axis parallel with the coil axis but is positioned outside of the magnetic field, a source of radiation adapted to be directed to the mirror and reflected therefrom to be recorded, means for mounting the coil and the field structure and its poles for simultaneous movement about a center coinciding with the point of reflection of the mirror and in a plane extending parallel to the direction of the magnetic field passing between the poles, and means for adjustably position ng the coil mounting and poles about said center.

14. A galvanometer comprising, a field structure including spaced opposed magnetic poles and a source of magnetic lines of force, a coil mounted for rotation on an axis between the opposed poles, a mirror associated with the coil so that t moves with the coil about an axis parallel with the coil axis, a source of radiation adapted to be directed to the mirror and reflected there- 'from so as to be recorded, said mirror being so mounted that a beam directed to and reflected from the mirror will be in a plane extending in the direction of the magnetic field, and means for adjusting the field structure and its poles together with the coil and the mirror so they will move as a unit parallel to the plane of the mag" netic field passing between the poles and about a center coinciding with the point of reflection of the mirror.

CARL A. HEILAND.

REFERENCES CITED The following references are of record in the file of this patent:

Number Redmond Nov, 13, 1945 

